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Suppression of gold nanoparticle agglomeration and its separation via nylon membranes

Chinese Journal of Chemical Engineering 2017年第7期25卷 931-937页

作者： Ayyavoo Jayalakshmi In-Chul Kim Young-Nam kwon School of Urban and Environmental Engineering Ulsan National Institute of Sdence and TechnologyUlsan 689-798Korea KIST-UNIST UIsan Center for Convergent Materials UNIST(Ulsan National Institute of Science and Technology)Korea Environment and Resources Research Center Korea Research Institute Chemical TechnologyDaejeon 305-606Korea

Use of ultraporous nylon membrane is one of the most widely employed techniques for removal of hard and soft nanoparticles in the semiconductor industry, and the accurate determination of membrane pore size is necessary in order to avoid manufacturing defects caused by contamination. The gold nanoparticle has several benefits for the evaluation of polymeric membranes; however, the nanoparticles agglomerate easily on the nylon membrane and make it difficult to evaluate the membrane precisely. The properties of 2-amino-2-hydroxymethyl-1,3-propanediol(ADP) ligand in gold nanoparticle solution were systematically investigated, and ADP was utilized for improved evaluation of the nylon membranes. Nylon membrane used in this study was prepared by phase inversion techniques. Ultrathin dense layer on top of the membrane surface and Darcy structures in the microporous membrane support were observed. The gold particle rejection was carried out at various p H values from 4 to14 and higher rejection was observed at p H 4 and 8. The suppression of gold colloid agglomeration using ADP and monodispersity of gold colloids was also analyzed by confocal laser scanning microscopy(CLSM), transmission electron microscopy(TEM), and scanning electron microscopy(SEM). van der Waals interaction energy of the particles was reduced in the addition of ADP. The presence of ADP ligand in the gold solutions prevented the agglomeration of gold nanoparticles and reduced the adsorption of the particles on the nylon membrane surface,leading to precise evaluation of membrane pore sizes.

关键词： Particle size Electron microscopy Gold colloid flock Semiconductor

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Use of gene-editing technology to introduce targeted modifications in pigs

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Journal of Animal Science and Biotechnology 2018年第2期9卷 268-277页

作者： Junghyun ryu Randall S.Prather Kiho Lee Department of Animal and Poultry Sciences Virginia Tech175 W.Campus DriveBlacksburgVA 24061USA Division of Animal Science University of Missouri-Columbia920 East Campus DriveColumbiaMO 65211USA National Swine Resource and Research Center University of Missouri-ColumbiaColumbiaMO 65211USA

Pigs are an important resource in agriculture and serve as a model for human diseases. Due to their physiological and anatomical similarities with humans, pigs can recapitulate symptoms of human diseases, making them a useful model in biomedicine. However, in the past pig models have not been widely used partially because of the difficulty in genetic modification. The lack of true embryonic stem cells in pigs forced researchers to utilize genetic modification in somatic cells and somatic cell nuclear transfer(SCNT) to generate genetically engineered(GE) pigs carrying site-specific modifications. Although possible, this approach is extremely inefficient and GE pigs born through this method often presented developmental defects associated with the cloning process. Advancement in the gene-editing systems such as Zinc-Finger Nucleases(ZFNs), Transcription activator-like effector nucleases(TALENs), and the Clustered regularly interspaced short palindromic repeat(CRISPR)/CRISPR-associated 9(Cas9) system have dramatically increased the efficiency of producing GE pigs. These gene-editing systems, specifically engineered endonucleases, are based on inducing double-stranded breaks(DSBs) at a specific location, and then site-specific modifications can be introduced through one of the two DNA repair pathways: non-homologous end joining(NHEJ) or homology direct repair(HDR).Random insertions or deletions(indels) can be introduced through NHEJ and specific nucleotide sequences can be introduced through HDR, if donor DNA is provided. Use of these engineered endonucleases provides a higher success in genetic modifications, multiallelic modification of the genome, and an opportunity to introduce site-specific modifications during embryogenesis, thus bypassing the need of SCNT in GE pig production. This review will provide a historical prospective of GE pig production and examples of how the gene-editing system, led by engineered endonucleases, have improved GE pig production. We wil

关键词： CRISPR/Cas9 Gene-editing Genetic engineering Knock-in Knockout Pig TALEN ZFN

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VQT:value cardinality and query pattern based R-schema to XML schema translation with implicit referential integrity

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2008年第12期9卷 1694-1707页

作者： Jinhyung KIM Dongwon JEONG Doo-kwon BAIK Department of Computer Science and Engineering Korea UniversitySeoul 136-713Korea Department of Informatics and Statistics Kunsan National UniversityKunsan 573-701Korea

In this paper,we propose a new relational schema (R-schema) to XML schema translation algorithm, VQT, which analyzes the value cardinality and user query patterns and extracts the implicit referential integrities by using the cardinality property of foreign key constraints between columns and the equi-join characteristic in user queries. The VQT algorithm can apply the extracted implied referential integrity relation information to the R-schema and create an XML schema as the final result. Therefore, the VQT algorithm prevents the R-schema from being incorrectly converted into the XML schema, and it richly and powerfully represents all the information in the R-schema by creating an XML schema as the translation result on behalf of the XML DTD.

关键词： Value cardinality Query pattern Relational schema XML schema Implicit referential integrity relations Explicit referential integrity

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Effect of the protection layer formed by cross-linked gelatin on the stability and performance of glucose and oxygen fuel cells

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Journal of Energy Chemistry 2021年第10期30卷 155-162,I0005页

作者： Kyuhwan Hyun Joonyoung Lee Suhyeon Kang Yongchai kwon Graduate School of Energy and Environment Seoul National University of Science and Technology232 Gongneung-roNowon-guSeoul 01811Republic of Korea Department of Chemical and Biomolecular Engineering Seoul National University of Science and Technology232 Gongneung-roNowon-guSeoul 01811Republic of Korea

A glucose oxidation catalyst comprising carbon nanotube,tetrathiafulvalene(TTF),gelatin,glutaraldehyde(GA)and glucose oxidase(GOx)(CNT/[TTF-GOx]/Gelatin+GA)is suggested to enhance the reactivity of glucose oxidation reaction(GOR),and the performance and stability of enzymatic biofuel cells(EBCs)using this *** this catalyst,TTF is used as mediator to transfer electron effectively,while GA is crosslinked to gelatin to form non-soluble *** structure prevents the dissolution of gelatin from aqueous electrolyte and reduces the leaching-out of GOx and TTF *** confirm the crosslinking effect of GA and gelatin,Fourier-transform infrared spectroscopy(FT-IR)and electrochemical evaluations are *** to FT-IR analysis,it was observed that the amide I peak shifted after *** is evidence showing the appropriate network formation and the reactivity of CNT/[TTFGOx]/Gelatin+GA is well preserved even after multiple potential *** addition,its GOx activity is regularly monitored for one month and the measurements prove that the structure prevents the leaching out of GOx *** on that,EBC using the anodic catalyst shows excellent performances,such as open circuit voltage of 0.75 V and maximum power density of 184μW/cm^(2).

关键词： Enzymatic biofuel cell Tetrathiafulvalene Crosslinking of glutaraldehyde and gelatin Hemi-acetal bond group

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An alternative interpretation for the map expression of "abrupt" changes in lateral stratigraphic level near transverse zones in fold-thrust belts

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Geoscience Frontiers 2012年第4期3卷 401-406页

作者： Sanghoon kwon Gautam Mitra Department of Earth System Sciences Yonsei UniversitySeoul 120-749Republic of Korea Department of Earth and Environmental Sciences University of RochesterRochesterNY 14627USA

The map expression of ＂abrupt＂ changes in lateral stratigraphic level of a thrust fault has been traditionally interpreted to be a result of the presence of （1） a lateral （or oblique） thrust-ramp, or （2） a frontal ramp with displacement gradient, and/or （3） a combination of these geometries. These geometries have been used to interpret the structures near transverse zones in fold-thrust belts （FTB）. This contribution outlines an alternative explanation that can result in the same map pattern by lateral variations in stratigraphy along the strike of a low angle thrust fault. We describe the natural example of the Leamington transverse zone, which marks the southern margin of the Pennsylvanian-Permian Oquirrh basin with genetically related lateral stratigraphic variations in the North American Sevier FTB. Thus, the observed map pattern at this zone is closely related to lateral stratigraphic variations along the strike of a horizontal fault. Even though the present-day erosional level shows the map pattern that could be interpreted as a lateral ramp, the observed structures along the Leamington zone most likely share the effects of the presence of a lateral （or oblique） ramp, lateral stratigraphic variations along the fault trace, and the displacement gradient.

关键词： Lateral stratigraphic changes Fold-thrust belt Transverse zone Frontal ramp Lateral ramp Displacement gradient

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Spatial Multi-Presence System to Increase Security Awareness for Remote Collaboration in an Extended Reality Environment

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Intelligent Automation & Soft Computing 2023年第7期37卷 369-384页

作者： Jun Lee Hyun kwon Department of Game Software Hoseo UniversityAsan-siKorea Department of Artificial Intelligence and Data Science Korea Military AcademySeoulKorea

Enhancing the sense of presence of participants is an important issue in terms of security awareness for remote collaboration in extended ***,conventional methods are insufficient to be aware of remote situations and to search for and control remote *** study pro-poses a spatial multi-presence system that simultaneously provides multiple spaces while rapidly exploring these spaces as users perform collaborative work in an extended reality *** proposed system provides methods for arranging and manipulating remote and personal spaces by creating an annular screen that is invisible to the *** user can freely arrange remote participants and their workspaces on the annular *** users can simultaneously view various spaces arranged on the annular screen,they can perform collaborative work while simultaneously feeling the presence of multiple spaces and can be fully immersed in a specific *** addition,the personal spaces where users work can also be arranged through the annular *** to the results of the performance evaluations,users participating in remote collaborative works can visualize the spaces of multiple users simultaneously and feel their presence,thereby increasing their understanding of the ***,the proposed system reduces the time to perform tasks and gain awareness of the emergency in remote workspaces.

关键词： Extended reality spatial presence multi presence security awareness

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Experimental Investigation of Flexible Hawkmoth-like Wings on the Wing-wake Interaction in Hovering Flight

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Journal of Bionic Engineering 2018年第1期15卷 139-153页

作者： YeongGyun ryu Jo Won Chang Joon Chung Dong-Ha Kim Department of Aerospace Engineering Ryerson University Toronto Ontario M5B 2K3 Canada Department of Aeronautical Science and Flight Operation Korea Aerospace University 76 Hanggongdaehak-ro Deogyang-gu Goyang-si Gyeonggi-do 10540 Republic of Korea Aerodynamics Group Korean Air R&D Center Daejeon Metropolitan City 34054 Republic of Korea

To study wing-wake interaction for various wing flexibilities, force measurements and digital particle image velocimetry were carried out on flapping hawkmoth-like wings in a water tank. Wing thickness was employed as a design variable for the wing flexi- bility distributions. Abrupt flap-down and phase delay in flexible wings influenced the behaviors of the Leading-Edge Vortex （LEV） and Trailing-Edge Vortex （TEV）, generated by the previous stroke. While the rigid wing exhibited a detached LEV at the end of the stroke, wing with specific flexibilities obtained attached LEVs. The attached LEVs induced a relatively rapid flow toward the wing surface as a result of encountering the TEV, and the flow caused a higher lift peak. On the other hand, the wings with larger wing deformations generated distinctive changes in LEV and TEV behaviors. The flap-down helped the TEV form closer to the wing surface, and it thus caused a downwash rather than wing-wake interaction. Furthermore, the most flexible wing had a newly-formed pair of LEVs above the wing during the wing reversal, thereby being not able to generate the wing-wake interaction. These results help to understand the different vortex structures generated by flexible wings during the wing reversal and the corresponding effects of wing-wake interaction.

关键词： hovering flight flexible hawkmoth wings wing-wake interaction Digital Particle Image Velocimetry (DPIV)

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Development and Application of a Production Data Analysis Model for a Shale Gas Production Well

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Fluid Dynamics & Materials Processing 2020年第3期16卷 411-424页

作者： Dongkwon Han Sunil kwon Department of Energy and Mineral Resources Dong-A UniversityBusan49315Korea

This paper presents the development and application of a production data analysis software that can analyze and forecast the production performance and reservoir properties of shale gas *** theories used in the study were based on the analytical and empirical *** reliability has been confirmed through comparisons with a commercial *** transient data relating to multi-stage hydraulic fractured horizontal wells,it was confirmed that the accuracy of the modified hyperbolic method showed an error of approximately 4%compared to the actual estimated ultimate recovery(EUR).On the basis of the developed model,reliable productivity forecasts have been obtained by analyzing field production data relating to wells in *** EUR was computed as 9.6 Bcf using the modified hyperbolic *** the Pow Law Exponential method,the EUR would be 9.4 *** models developed in this study will allow in the future integration of new analytical and empirical theories in a relatively readily than commercial models.

关键词： Production data analysis shale gas multi-stage hydraulic fractured horizontal wells estimated ultimate recovery

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Flapping dynamics of a flexible propulsor near ground

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Acta Mechanica Sinica 2016年第6期32卷 991-1000页

作者： Jaeha ryu Sung Goon Park Boyoung Kim Hyung Jin Sung Department of Mechanical Engineering Korea Advanced Institute of Science and Technology

The flapping motion of a flexible propulsor near the ground was simulated using the immersed boundary method. The hydrodynamic benefits of the propulsor near the ground were explored by varying the heaving frequency (St) of the leading edge of the flexible propulsor. Propulsion near the ground had some advantages in generating thrust and propelling faster than propulsion away from the ground. The mode analysis and flapping amplitude along the Lagrangian coordinate were examined to analyze the kinematics as a function of the ground proximity (d) and St. The trailing edge amplitude (\(a_\mathrm{tail}\)) and the net thrust (\(\overline{{F}}_x\)) were influenced by St of the flexible propulsor. The vortical structures in the wake were analyzed for different flapping conditions.

关键词： Flexible propulsor Ground effect Immersed boundary method Mode analysis

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Early treadmill exercise increases macrophage migration inhibitory factor expression after cerebral ischemia/reperfusion

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Neural Regeneration Research 2019年第7期14卷 1230-1236页

作者： Min Cheol Chang Chae Ri Park Seung Hwa Rhie Woo Hyun Shim Dae yul Kim Department of Rehabilitation Medicine College of MedicineYeungnam University Asan Institute for Life Sciences Asan Medical CenterUniversity of Ulsan College of Medicine Department of Rehabilitation Medicine Asan Medical CenterUniversity of Ulsan College of Medicine Department of Radiology Asan Medical CenterUniversity of Ulsan College of Medicine

The neuroprotective function of macrophage migration inhibitory factor(MIF) in ischemic stroke was rarely *** study aimed to investigate the effects of early treadmill exercise on recovery from ischemic stroke and to determine whether these effects are associated with the expression levels of MIF and brain-derived neurotrophic factor(BDNF) in the ischemic area.A total of 40 male Sprague-Dawley rats were randomly assigned to the ischemia and exercise group [middle cerebral artery occlusion(MCAO)-Ex,n = 10),ischemia and sedentary group(MCAO-St,n = 10),sham-surgery and exercise group(Sham-Ex,n= 10),or sham-surgery and sedentary group(Sham-St,n = 10).The MCAO-Ex and MCAO-St groups were subjected to MCAO for 60 minutes,whereas the Sham-Ex and Sham-St groups were subjected to an identical operation without *** in the MCAO-Ex and Sham-Ex groups then ran on a treadmill for 30 minutes once a day for 5 consecutive *** reperfusion,the hanging time tested by the wire hang test was longer and the relative fractional anisotropy determined by MRI was higher in the peri-infarct region of the MCAO-Ex group compared with the MCAO-St *** expression levels of MIF and BDNF in the peri-infarct region were upregulated in the MCAO-Ex *** MIF and BDNF levels were positively correlated with relative fractional anisotropy changes in the peri-infarct *** was no significant difference in the levels of MIF and BDNF in the peri-infarct region between the Sham-Ex and Sham-St *** study demonstrated that early exercise(initiated 48 hours after the MCAO) could improve motor and neuronal recovery after ischemic ***,the increased levels of MIF and BDNF in the peri-infarct region(penumbra) may be one of the mechanisms of enhanced neurological function *** experiments were approved by the Institutional Animal Care and Use Committee in Asan Medical Center in South Korea(2016-12-126).

关键词： ischemic stroke early exercise macrophage migration inhibitory factor brain-derived neurotrophic factor motor recovery neural regeneration

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